MnO2 on eliminating Al2TiO5 and promoting microwave dielectric properties of 0.90Al2O3–0.10TiO2 composite ceramics

Abstract

0.90Al2O3–0.10TiO2 ceramics have been synthesized by the conventional solid-state method. xmol% MnO2 (x = 0.6, 0.7, 0.8, 0.9) was added into the system to eliminate the impurity phase of Al2TiO5, and ultimately improve the microwave dielectric properties. For MnO2 added 0.90Al2O3–0.10TiO2 ceramics Al2TiO5 phase was suppressed without annealing treatment, during the sintering temperature range from 1200 to 1350 °C. In combination with scanning electron microscope micrographs, the optimized sintering temperature is 1250 °C, due to the abnormal grain growth occurred in higher sintering temperature. The grain size increased slightly with the growing content of MnO2. In particular, 0.90Al2O3–0.10TiO2 with 0.8 mol% MnO2 sintered at 1250 °C for 4 h exhibited the most compact uniform microstructure, and presented great microwave dielectric properties : e r = 12.5, Q × f = 119,539 GHz, τ f = 0.11 ppm/°C.